This invention relates to lubricating compositions that are useful as industrial or automotive gear lubricants. These compositions provide antiwear/extreme-pressure protection, thermally stability, and have good demulsifying properties.
For gear assemblies in the automotive and industrial gear areas, one major problem for lubricating compositions is providing antiwear and extreme-pressure protection. Each of these different type gear assemblies pose a different wear problem for lubricants. When a single lubricant provides protection for both these areas, it is known as a Universal gear oil. It is difficult to provide a lubricating composition that can provide protection to both the automotive gear assembly, with it high shearing and shock loading wear problems, and industrial gear assemblies that have rolling wear from it spur gears.
In addition to antiwear and extreme pressure protection as well as stability, including oxidation and thermal stability issues, lubricating compositions in the universal gear oils such as those used in the automotive and industrial gear oil areas must provide protection for the soft metal components of the gears. These soft metal components are typically copper and brass related components of the equipment. Traditionally copper deactivators have been added to prevent adverse effects of the lubricating composition, especially the organic polysulfides on the copper and soft metal components. Triazoles have been used as one of these additives. However, triazoles adversely effect the lubricating composition""s ability to provide protection under shock-loading conditions such as those measured in the SAE L-42 test.
Cleanliness is a measure of the stability of the lubricant and is measured as results in the SAE L-60-1 test. At automotive gear oil treatment levels, the lubricant must provide a level of cleanliness acceptable in these tests. One approach for controlling cleanliness in an engine is to provide a dispersant to the lubricating compositions. The dispersant acts to suspense sludge and soot particles and emulsify the lubricating compositions.
It is difficult for lubricant formulators to provide an additive combination that is effective as a universal lubricant in both automotive and industrial gears. Additionally, it is difficult to provide additive combinations that provide the antiwear and extreme-pressure protection and have thermal stability without adversely effecting demulsibility properties of the lubricants. Further, it is difficult to provide protection for copper and soft metal components without adversely effecting the lubricant""s ability to provide shock-loading protection. It is desirable to find a combination of additives that can provide performance under these various conditions.
The invention relates to a lubricating composition comprising: (a) at least one sulfur-free hydrocarbyl phosphoric acid ester or salt, (b) at least one sulfur-containing hydrocarbyl phosphoric acid or salt, (c) an organic polysulfide, (d) at least one dispersant, and (e) at least one triazole metal deactivator. The composition may also include a thiadiazole derivative. This additive combination provides good antiwear and thermal stability properties, even under severe thermal conditions. These compositions also have good demulsibility properties.
The above combination of additives provides the antiwear and extreme-pressure protection necessary for automotive and industrial gear applications. These additives additionally provide this protection without adversely effecting demulsibility properties of the lubricant.
The term xe2x80x9chydrocarbylxe2x80x9d includes hydrocarbon as well as substantially hydrocarbon groups. Substantially hydrocarbon describes groups that contain heteroatom substituents that do not alter the predominantly hydrocarbon nature of the group. Examples of hydrocarbyl groups include the following:
(1) hydrocarbon substituents, i.e., aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, aromatic-, aliphatic- and alicyclic-substituted aromatic substituents and the like as well as cyclic substituents wherein the ring is completed through another portion of the molecule (that is, for example, any two indicated substituents may together form an alicyclic radical);
(2) substituted hydrocarbon substituents, i.e., those substituents containing non-hydrocarbon groups that, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent; those skilled in the art will be aware of such groups (e.g., halo (especially chloro and fluoro), hydroxy, mercapto, nitro, nitroso, sulfoxy, etc.);
(3) heteroatom substituents, i.e., substituents that will, while having a predominantly hydrocarbon character within the context of this invention, contain an atom other than carbon present in a ring or chain otherwise composed of carbon atoms (e.g., alkoxy or alkylthio). Suitable heteroatoms will be apparent to those of ordinary skill in the art and include, e.g., sulfur, oxygen, nitrogen and such substituents as, e.g., pyridyl, furyl, thienyl, imidazolyl, etc.
In general, no more than about 2, preferably no more than one, hetero substituent will be present for every 10 carbon atoms in the hydrocarbyl group. Typically, there will be no such heteroatom substituents in the hydrocarbyl group. Therefore, the hydrocarbyl group is purely hydrocarbon.
In the specification and appended claims, the term xe2x80x9clubricating compositionxe2x80x9d refers to the combination of an oil of lubricating viscosity plus additives. The percentages of components are by weight are based on the total amount of the additive and the oil of lubricating viscosity. If not specifically stated, the oil of lubricating viscosity makes up the balance of the lubricating composition.
The lubricating compositions have two phosphorus antiwear agents. The antiwear and/or extreme pressure properties are provided by the combination of the sulfur-free and sulfur-containing phosphoric acid esters. The phosphoric acid esters are each independently present in an amount from about 0.05% to about 5%, or from about 0.08% to about 3%, or from about 0.1% to about 1% by weight. In one embodiment, the lubricating composition is an automotive gear oil. In this embodiment the phosphoric acid ester are each independently present in an amount from about 0.05% to about 5%, or from about 0.07% to about 3%, or from about 0.1% to about 1% by weight. In another embodiment, the lubricating composition is an industrial gear oil. In this embodiment, the phosphoric acid esters are each independently present in an amount from about 0.01% to about 1%, or from about 0.05% to about 0.7%, or from about 0.8% to about 0.5% by weight. Here and elsewhere in the specification and claims, range and ratio limits may be combined. In one embodiment, the phosphorus esters are present in a weight ratio from about 0.5 to about 2, or from about 0.75 to about 1.5 or from about 1 part sulfur-free phosphoric acid ester to 1 part of sulfur-containing phosphoric acid ester.
Sulfur-free Phosphoric Acid Esters
The sulfur-free phosphoric acid esters are those lacking a sulfur phosphorus bond. These esters are, in one embodiment, free of sulfur atoms. These esters at present at an amount to provide antiwear and/or extreme pressure properties to the lubricating composition.
The sulfur-free phosphoric acid ester may be prepared by reacting one or more sulfur-free phosphorus acids or anhydrides with one or more alcohols containing from 1 to about 30, or from 2 to about 24, or from about 3 to about 12 carbon atoms. The phosphorus acid or anhydride is generally an inorganic phosphorus reagent, such as phosphorus pentoxide, phosphorus trioxide, phosphorus tetroxide, phosphorous acid, phosphoric acid, phosphorus halide, or one or more C1-7 phosphorus esters. The alcohols generally contain from one to about 30, or from two to about 24, or from about 3 to about 12, or up to about 8 carbon atoms. Alcohols used to prepare the phosphoric acid esters include butyl, amyl, 2-ethylhexyl, hexyl, octyl, oleyl, and cresol alcohols. Examples of commercially available alcohols include Alfol 810 (a mixture of primarily straight chain, primary alcohols having from 8 to 10 carbon atoms); Alfol 1218 (a mixture of synthetic, primary, straight-chain alcohols containing 12 to 18 carbon atoms); Alfol 20+ alcohols (mixtures of C18-C28 primary alcohols having mostly C20 alcohols as determined by GLC (gas-liquid-chromatography); and Alfol 22+ alcohols (C18-C28 primary alcohols containing primarily C22 alcohols). Alfol alcohols are available from Continental Oil Company. Another example of a commercially available alcohol mixtures are Adol 60 (about 75% by weight of a straight chain C22 primary alcohol, about 15% of a C20 primary alcohol and about 8% of C18 and C24 alcohols) and Adol 320 (oleyl alcohol). The Adol alcohols are marketed by Ashland Chemical.
A variety of mixtures of monohydric fatty alcohols derived from naturally occurring triglycerides and ranging in chain length of from C8 to C18 are available from Procter and Gamble Company. These mixtures contain various amounts of fatty alcohols containing mainly 12, 14, 16 or 18 carbon atoms. For example, CO-1214 is a fatty alcohol mixture containing 0.5% of C10 alcohol, 66.0% of C12 alcohol, 26.0% of C14 alcohol and 6.5% of C16 alcohol.
Another group of commercially available mixtures include the xe2x80x9cNeodolxe2x80x9d products available from Shell Chemical Co. For example, Neodol 23 is a mixture of C12 and C13 alcohols; Neodol 25 is a mixture of C12 and C15 alcohols; and Neodol 45 is a mixture of C14 to C15 linear alcohols. Neodol 91 is a mixture of C9, C10 and C11 alcohols.
Fatty vicinal diols also are useful and these include those available from Ashland Oil under the general trade designation Adol 114 and Adol 158. The former is derived from a straight chain alpha-olefin fraction of C11-C14, and the latter is derived from a C15-C18 alpha-olefin fraction.
The amine salt of a phosphoric acid ester is prepared by reacting a phosporic acid ester with ammonia or a basic nitrogen compound, such as an amine or a nitrogen containing dispersant. The salts may be formed separately, and then the salt of the phosphorus acid ester may be added to the lubricating composition. Alternatively, the salts may also be formed in situ when the acidic phosphorus acid ester is blended with other components to form a fully formulated lubricating composition.
The ammonium salts of the phosphorus acid esters may be formed from ammonia, or an amine, or mixtures thereof. These amines may be monoamines or polyamines. Useful amines include those disclosed in U.S. Pat. No. 4,234,435 at Col. 21, line 4 to Col. 27, line 50, incorporated herein by reference.
The monoamines generally contain from 1 to about 24, or from 1 to about 12, or from 1 to about 6 carbon atoms. Examples of monoamines include methylamine, ethylamine, propylamine, butylamine, 2-ethylhexylamine, octylamine, and dodecylamine. Examples of secondary amines include dimethylamine, diethylamine, dipropylamine, dibutylamine, methylbutylamine, ethylhexylamine, etc. Tertiary amines include trimethylamine, tributylamine, methyldiethylamine, ethyldibutylamine, etc.
In one embodiment, the amine is a fatty (C8-30) amine such as n-octylamine, n-decylamine, n-dodecylamine, n-hexadecylamine, n-octadecylamine, oleyamine, etc. Also fatty amines include xe2x80x9cArmeenxe2x80x9d amines (products available from Akzo Chemicals, Chicago, Illinois), such Armeen C, Armeen O, Armeen T, and Armeen S, wherein the letter designates the fatty group, such as coco, oleyl, tallow, or stearyl groups.
Other useful amines include primary ether amines, such as those represented by the formula, Rxe2x80x3(ORN)xNH2, wherein RN is a divalent alkylene group having about 2 to about 6 carbon atoms; x is a number from 1 to about 150, or from about 1 to about 5, or 1; and Rxe2x80x3 is a hydrocarbyl group of about 5 to about 150 carbon atoms. An example of an ether amine is available under the name SURFAM(copyright) amines produced and marketed by Mars Chemical Company, Atlanta, Ga. Useful etheramines are exemplified by those identified as SURFAM P14B (decyloxypropylamine), SURFAM P16A (linear C16), SURFAM P17B (tridecyloxypropylamine). The carbon chain lengths (i.e., C14, etc.) of the SURFAMS described above and used hereinafter are approximate and include the oxygen ether linkage.
In one embodiment, the amine is a tertiary-aliphatic primary amine. Generally, the aliphatic group, generally an alkyl group, contains from about 4 to about 30, or from about 6 to about 24, or from about 8 to about 22 carbon atoms. Such amines are illustrated by t-butylamine, t-hexylamine, 1-methyl-1-amino-cyclohexane, t-octylamine, t-decylamine, t-dodecylamine, t-tetradecylamine, t-hexadecylamine, t-octadecylamine, t-tetracosanylamine, and t-octacosanylamine. The amine may be mixtures of tertiary aliphatic amines such as xe2x80x9cPrimene 81 Rxe2x80x9d (a mixture of C11-C14 tertiary alkyl primary amines) and xe2x80x9cPrimene JMTxe2x80x9d (a mixture of C18-C22 tertiary alkyl primary amines). These amines are available from Rohm and Haas Company. The tertiary aliphatic primary amine useful for the purposes of this invention and methods for their preparation are described in U.S. Pat. No. 2,945,749, incorporated by reference for its teaching in this regard.
In one embodiment, the amine may be a hydroxyamine. Typically, the hydroxyamines are primary, secondary, or tertiary alkanol amines or mixtures thereof. Such amines can be represented by the formulae: H2)N)Rxe2x80x2)OH, H(Rxe2x80x21)N)Rxe2x80x2)OH, and (Rxe2x80x21)2)N)Rxe2x80x2)OH, wherein each Rxe2x80x21 is independently a hydrocarbyl group having from 1 to about 8 carbon atoms or hydroxyhydrocarbyl group having from one to about eight carbon atoms, or from one to about four, and Rxe2x80x2 is a divalent hydrocarbyl group of about 2 to about 18 carbon atoms, or from 2 to about 4. The group -Rxe2x80x2-OH in such formulae represents the hydroxyhydrocarbyl group. Rxe2x80x2 can be an acyclic, alicyclic or aromatic group. Typically, Rxe2x80x2 is an acyclic straight or branched alkylene group, such as an ethylene, 1,2-propylene, 1,2-butylene, and 1,2-octadecylene groups. Where two Rxe2x80x21 groups are present in the same molecule they can be joined by a direct carbon-to-carbon bond or through a heteroatom (e.g., oxygen, nitrogen or sulfur) to form a 5-, 6-, 7- or 8-membered ring structure. Typically, however, each Rxe2x80x21 is independently a methyl, ethyl, propyl, butyl, pentyl or hexyl group. Examples of these alkanolamines include mono-, di-, and triethanolamine, diethylethanolamine, ethylethanolamine, butyldiethanolamine, etc.
The hydroxyamines may also be an ether N-(hydroxyhydrocarbyl)amine. These are hydroxypoly(hydrocarbyloxy) analogs of the above-described hydroxyamines (these analogs also include hydroxyl-substituted oxyalkylene analogs). Such N-(hydroxyhydrocarbyl) amines can be conveniently prepared by reaction of one or more of the epoxides described herein with afore-described amines and may be represented by the formulae: H2N)(Rxe2x80x2O)x)H, H(Rxe2x80x21))N)(Rxe2x80x2O)x)H, and (Rxe2x80x21)2)N)(Rxe2x80x2O)x)H, wherein x is a number from about 2 to about 15 and Rxe2x80x21 and Rxe2x80x2 are as described above. Rxe2x80x21 may also be a hydroxypoly(hydrocarbyloxy) group. Useful hydroxyhydrocarbyl amines include 2-hydroxyethylhexylamine; 2-hydroxyethyloctylamine; 2-hydroxyethylpentadecylamine; 2-hydroxyethyloleylamine; 2-hydroxyethylsoyamine; bis(2-hydroxyethyl)hexylamine; bis(2-hydroxyethyl)oleylamine; and mixtures thereof.
In one embodiment, the amine may be a hydroxyhydrocarbyl amine. These hydroxyhydrocarbyl amines are available from the Akzo Chemical Division of Akzona, Inc., Chicago, Ill., under the general trade designations xe2x80x9cEthomeenxe2x80x9d and xe2x80x9cPropomeen.xe2x80x9d Specific examples of such products include: Ethomeen C/15; Ethomeen C/20 and C/25; Ethomeen O/12; Ethomeen S/15 and S/20; Ethomeen T/12, T/15 and T/25; and Propomeen O/12.
The amine may also be a polyamine. The polyamines include alkoxylated diamines, fatty polyamine diamines, alkylenepolyamines, hydroxy containing polyamines, condensed polyamines, arylpolyamines, and heterocyclic polyamines. Commercially available examples of alkoxylated diamines include Ethoduomeen T/13 and T/20, which are ethylene oxide condensation products of N-tallowtrimethylenediamine containing 3 and 10 moles of ethylene oxide per mole of diamine, respectively.
In another embodiment, the polyamine is a fatty diamine. The fatty diamines include mono- or dialkyl, symmetrical or asymmetrical ethylenediamines, propanediamines (1,2 or 1,3), and polyamine analogs of the above. Suitable commercial fatty polyamines are Duomeen C (N-coco-1,3-diaminopropane), Duomeen S (N-soya-1,3-diaminopropane), Duomeen T (N-tallow-1,3-diaminopropane), and Duomeen O (N-oleyl-1,3-diaminopropane). xe2x80x9cDuomeensxe2x80x9d are commercially available from Armak Chemical Co., Chicago, Ill.
In another embodiment, the amine is an alkylenepolyamine. Alkylenepolyamines are represented by the formula HR4N-(Alkylene-N)n-(R4)2, wherein each R4 is independently hydrogen; or an aliphatic or hydroxy-substituted aliphatic group of up to about 30 carbon atoms; n is a number from 1 to about 10, or from about 2 to about 7, or from about 2 to about 5; and the xe2x80x9cAlkylenexe2x80x9d group has from 1 to about 10 carbon atoms, or from about 2 to about 6, or from about 2 to about 4. In another embodiment, R4 is defined the same as Rxe2x80x21 above. Such alkylenepolyamines include methylenepolyamines, ethylenepolyamines, butylenepolyamines, propylenepolyamines, pentylenepolyamines, etc. Specific examples of such polyamines are ethylenediamine, triethylenetetramine, tris-(2-aminoethyl)amine, propylenediamine, trimethylenediamine, tripropylenetetramine, triethylenetetraamine, tetraethylenepentamine, hexaethyleneheptamine, pentaethylenehexamine, etc. Higher homologs obtained by condensing two or more of the above-noted alkyleneamines are similarly useful as are mixtures of two or more of the aforedescribed polyamines.
In one embodiment, the polyamine is an ethylenepolyamine. Such polyamines are described in detail under the heading Ethylene Amines in Kirk Othmer""s xe2x80x9cEncyclopedia of Chemical Technology,xe2x80x9d 2d Edition, Vol. 7, pages 22-37, Interscience Publishers, New York (1965). Ethylenepolyamines are often a complex mixture of polyalkylenepolyamines including cyclic condensation products. Other useful types of polyamine mixtures are those resulting from stripping of the above-described polyamine mixtures to leave, as residue, what is often termed xe2x80x9cpolyamine bottoms.xe2x80x9d In general, alkylenepolyamine bottoms can be characterized as having less than 2%, usually less than 1% (by weight) material boiling below about 200xc2x0 C. A typical sample of such ethylenepolyamine bottoms obtained from the Dow Chemical Company of Freeport, Tex. designated xe2x80x9cE-100xe2x80x9d has a specific gravity at 15.6xc2x0 C. of 1.0168, a percent nitrogen by weight of 33.15 and a viscosity at 40xc2x0 C. of 121 centistokes. Gas chromatography analysis of such a sample contains about 0.93% xe2x80x9cLight Endsxe2x80x9d (most probably diethylenetriamine), 0.72% triethylenetetraamine, 21.74% tetraethylenepentaamine and 76.61% pentaethylenehexamine and higher analogs. These alkylenepolyamine bottoms include cyclic condensation products such as piperazine and higher analogs of diethylenetriamine, triethylenetetramine and the like. These alkylenepolyamine bottoms may be reacted solely with the acylating agent or they may be used with other amines, polyamines, or mixtures thereof.
Another useful polyamine is a condensation reaction between at least one hydroxy compound with at least one polyamine reactant containing at least one primary or secondary amino group. The hydroxy compounds include polyhydric alcohols and amines. The polyhydric alcohols are described below. In one embodiment, the hydroxy compounds are polyhydric amines. Polyhydric amines include any of the above-described monoamines reacted with an alkylene oxide (e.g., ethylene oxide, propylene oxide, butylene oxide, etc.) having from two to about 20 carbon atoms, or from 2 to about 4. Examples of polyhydric amines include tri-(hydroxypropyl)amine, tris-(hydroxymethyl)amino methane, 2-amino-2-methyl-1,3-propanediol, N,N,Nxe2x80x2,Nxe2x80x2-tetrakis (2-hydroxypropyl) ethylenediamine, and N,N,Nxe2x80x2,Nxe2x80x2-tetrakis (2-hydroxyethyl) ethylenediamine. Tris(hydroxymethyl) aminomethane (THAM) is particularly useful.
Polyamines that may react with the polyhydric alcohol or amine to form the condensation products or condensed amines, are described above. Preferred polyamines include triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and mixtures of polyamines such as the above-described xe2x80x9camine bottoms.xe2x80x9d The condensation reaction of the polyamine reactant with the hydroxy compound is conducted at an elevated temperature, usually from about 60xc2x0 C. to about 265xc2x0 C., or from about 220xc2x0 C. to about 250xc2x0 C. in the presence of an acid catalyst.
The amine condensates and methods of making the same are described in PCT publication WO 86/05501 and U.S. Pat. No. 5,230,714 (Steckel), incorporated by reference for its disclosure to the condensates and methods of making. A particularly useful amine condensate is prepared from HPA Taft Amines (amine bottoms available commercially from Union Carbide Co. with typically 34.1% by weight nitrogen and a nitrogen distribution of 12.3% by weight primary amine, 14.4% by weight secondary amine and 7.4% by weight tertiary amine), and tris(hydroxymethyl)aminomethane (THAM).
In another embodiment, the polyamines are polyoxyalkylene polyamines, e.g. polyoxyalkylene diamines and polyoxyalkylene triamines, having average molecular weights ranging from about 200 to about 4000, or from about 400 to about 2000. The polyoxyalkylene polyamines are commercially available and may be obtained, for example, from the Jefferson Chemical Company, Inc. under the trade name xe2x80x9cJeffamines D-230, D-400, D-1000, D-2000, T-403, etc.xe2x80x9d U.S. Pat. Nos. 3,804,763 and 3,948,800 are expressly incorporated herein by reference for their disclosure of such polyoxyalkylene polyamines and acylated products made therefrom.
In another embodiment, the polyamines are hydroxy-containing polyamines. Hydroxy-containing polyamine analogs of hydroxy monoamines, particularly alkoxylated alkylenepolyamines, e.g., N,N-(diethanol)ethylene diamines can also be used. Such polyamines can be made by reacting the above-described alkylene amines with one or more of the alkylene oxides described herein. Similar alkylene oxide-alkanol amine reaction products may also be used such as the products made by reacting the above described primary, secondary or tertiary alkanol amines with ethylene, propylene or higher epoxides in a 1.1 to 1.2 molar ratio. Specific examples of hydroxy-containing polyamines include N-(2-hydroxyethyl) ethylenediamine, N,Nxe2x80x2-bis(2-hydroxyethyl)-ethylenediamine, 1-(2-hydroxyethyl)piperazine, mono(hydroxypropyl)-substituted tetraethylenepentamine, N-(3-hydroxybutyl)-tetramethylene diamine, etc.
In another embodiment, the polyamine is a heterocyclic polyamine. The heterocyclic polyamines include aziridines, azetidines, azolidines, tetra- and dihydropyridines, pyrroles, indoles, piperidines, imidazoles, di- and tetrahydroimidazoles, piperazines, isoindoles, purines, morpholines, thiomorpholines, N-aminoalkylmorpholines, N-aminoalkylthiomorpholines, N-aminoalkylpiperazines, N,Nxe2x80x2-diaminoalkylpiperazines, azepines, azocines, azonines, azecines and tetra-, di- and perhydro derivatives of each of the above and mixtures of two or more of these heterocyclic amines.